Method of and apparatus for storing gases



July 12, 1955 c. v. SPANGLER l 2,712,736

METHOD OF AND APPARATUS FOR STORING GASES Filed Oct. 11. 1951 nnentorCof/ V. fpafgy/ef @MYV/@MM Gttomegs United tates Patent ME'IGD 0F ANDAPPARATUS FR STORING GASES Pittsburgh, Pa., assigner to J. F.

Carl V. Spangler,

Kansas City, Mo., a corporation of Pritchard & Co., Missouri Thisinvention relates to a method of and apparatus for storing or stockpiling of gases, for example, hydrocarbon gases such as propane, methaneor natural gas such as the commercial pipe line gas which is nowdistributed on almost a nation-wide basis, the present application beingan improvement on the method and apparatus disclosed in my co-pendingapplication led May i4, 1949, Serial No. 93,384, now Patent No.2,663,626.

The principal object of the invention is the provision of a practical,safe and economical storage of the above mentioned gases throughadsorption by a solid adsorbent material at moderate pressures and at atemperature close to, at the liquefaction temperature of methane at thestorage pressure.

it is also an object of the invention to provide for release or" theadsorbed gas when the gas is desired for use or to augment the flowvolume in a pipe line at times of high demand.

In accomplishing these and other objects of the invention hereinafterdescribed, I have provided an improved method and apparatus which isdiagrammatically illustrated in the accompanying drawing wherein:

1 designates a pipe line leading from a supply of natural gas, forexample, a commercial high pressure gas transportation system by whichnatural gas is conveyed from a lield of production to a market which maybe many miles from the source of supply. Protable operation of suchsystems depend upon substantially full pipe line flow. Consequently,during times' of low demand for the gas, adequate storage must beprovided for the surplus gas which is made available for augmenting thepipe line flow during times of high market demand. This storage gas maybe taken at the start of the transportation system and at various pointsalong the length of the line where it is convenient to remove and storethe gas. It is therefore to be understood that the pipe line 1 merelyconnects a source for the gas to be stored in accordance with thepresent invention. It is also to be understood that such gas issubstantially methane although pipe line gas in addition to normalimpurities may contain carbon dioxide, nitrogen, traces of the raregases such as helium, argon, etc., limited amounts of vapor or gas ofthe heavier hydrocarbons such as ethane, propane, butaues, pentanes,etc. which are not removed from it completely in commercial practice.Essentially, however, the major ow is methane and therefore in thepresent description the terms methane and natural gas are usedsynonomously.

I have discovered that methane can be adsorbed as an adsorbate onadsorbent materials at temperatures near its liqueiaction temperature insuliicient amounts to make such storage system commercially practical.

ln carrying out the invention the gas to be stored is brought from theline l into the storage system through an orifice meter indicated at 2and passed through a puriiication plant 3 in which all traces of vaporphase moisture is removed from the gas together with any possible carbondioxide, hydrogen sulde, or other acid 4gases 2,712,730 ce Patented July12, 1955 which may be mixed in the main gas supply as impurities.

After purification the gas passes through a pipe 4 to a compressor 5from which the gas is conducted through a pipe 6 to an aftercooler 7 andthen through a pipe 8 to a heat exchanger 9 in which the gas isprechilled prior to discharge through a pipe 10 to a refrigeratingapparatus 11. The refrigeration apparatus may be of any suitable typeand utilize various methods of refrigeration depending upon theindividual situation. The temperature of the gas as it leaves therefrigerated apparatus will be just above the liquefaction temperatureof the methane at the operating pressure. The refrigerated gas is thenconducted through a pipe l2 to a separator 13 wherein those materialswhich have been liquefied or solidified are separated from gas stream.The liquid so removed will be through a pipe 14 to a separate outsidestorage system (not shown) and will not enter into any processingembodying the present invention, except as the refrigeration embodied inthis cold liquid may be used for precooling entering natural gas. Thevapor phase methane that is left in the system is conducted through apipe l5 into a condenser 16 wherein further heat removal from themethane causes it to condense. The refrigeration system used in thecondenser 16 may be any of several systems well known in the art of gasliquefacfrom the condenser 9 wherein the methane vapors serve to coolincoming methane. The methane vapors are then conducted and dischargedthrough a pipe 21 to the suction of the gas compressor 5 by way of apipe 22 connecting the pipes 21 with the pipe 4. By continual ow ofliquid methane into the adsorbent 19, the adsorbent will eventuallyreach temperatures closely approaching the temperature of the liquidmethane. When the adsorbent has been cooled to temperatures slightlyabove the temperature of liquid methane, methane will be adsorbed in thepores of the adsorbent and the liquid methane phase will disappearexcept for a possible slight visible wetting of the adsorbent.

As methane is adsorbed on the adsorbent, fresh gas will be brought intothe plant from line 1 to maintain the volume of the circulating systemsubstantially constant. When the adsorbent is saturated with methaneneed be removed. It

However, the quantities of gas which must be circulated are extremelylarge, furthermore, if gas circulation is used there is a temperaturegradient through the adsorbent which reduces its capacity to adsorb gasbelow the value obtained if the entire bed is'cooled to. a temperatureclosely approaching the liquefaction temperature.

they may be comprised of bottom 24 and a top 25 constructed withsubstantially tight joints to prevent direct leakage into and out of theVessel. The vessel is completely insulated preferably' is l.supplied bythe container. ln some cases ,nected to the discharge pipe Ztl.

by lining all the interior surfaces with an insulating material 26suiiicient to maintain the desired low temperature oiV the adsorbent.With this method of insulation, the walls of the vessel are protectedfrom becoming iriable and structurally unsafe at the extremely lowternperatures involved. Therefore, special expensive alloys andconstruction are not required as in cases Where the metal is indirectContact with low temperatures. in fact, such tanks as now used for largeoil or gas storage might be used with modifications for handling tieInaterials herein involved. lt is important, however, that the thicknessand nature of the insulating material be selected as the best availablefor the duty. Suitable insulating materials are readily obtained whichhave adequate strength, thermal capacities and general physical and`chemical qualications for the duty described. lt is also desirable toselect an insulation that is resistant to abrasion by the adsorbingmaterial. Such materials need only protection from the weather, whichfunction it may be desirable to install an inner liner 27 of thin sheetmetal or other material between the insulation and the adsorbent bed toprevent large circulating `currents. of gas from reaching the outervessel wall or to prevent the flow of liquid through the insulation.

The liquid from the condenser is discharged onto the adsorbent through adistribution system which in the illustrated instance comprises a header2d which connects the inlet pipe with a plurality of distribution ducts29 having perrorations through which the liquid methane is distributedsubstantially uniformly over the horizontal cross sectional area of thevessel.

A similar collection system of perforate ducts E@ is located at thebottom of the bed of adsorbent and con- The distributing and dischargesystems are formed of a suitable material to withstand the temperaturesinvolved. Since Vthe distributing and discharge systems are cooled bythe gas or liquid passing therethrough, insulating seals 3l areVrequired where the pipes pass through the walls or the vessel. A secondcompressor 32 is shown in connection with the pipes t and i5 throughintalce and discharge pipes 33 and 34.

Filling the space within the vessel Vis the body of solid adsorbentmaterial 19. The adsorbent material may be Vallowed to rest directly onthe insulating material on the bottom of the vessel and to hll outagainst the sides. ln turn the insulation across the top oi the vesseland above the adsorbent material may rest directly on the bed ofadsorbent. In order to take advantage of possible physicalcharacteristics of either insulation or adsorbent material, structuralprops or supports might be supplied if needed to take or distribute someof tre stress.

The adsorbent 1% may comprise one or a mixture o two or more of thewell-known adsorbent materials .such as an adsorbent clay, attapulgite,ullers earth, activated carbons and charcoals, bauKites, sintomas,calcium sulfate, silica or alumina gels, diatomaceous earth, etc. Thesematerials are all solids and may be prepared for use in a variety ofways.

When it becomes necessary and desirable to use the gas in storage, awarm methane or natural gas is circulated in suitable quantity by thecompressor 32 through thel pipes 33 and 34 to the condenser 16 which isnow used as a heater to increase the temperature of the circulated gas.The refrigeration apparatus is ,converted to a heating system bycirculating therethrough in heat exchange relation with the gas, heatfrom a source of supply indicated at 3d which might be a steam boilerplant, the steam being circulated through the pipe connections 56 and37V with the refrigerating coil. The heated gas is then passed throughthe distribution duct 2S into and through the adsorbent storage bed i9.On

passing through the adsorbent bed the comparatively warm gas adds heatto it, raising the temperature thereof, adding sensible heat to theadsorbent, and furnishing the latent heat of desorption for the methaneadsorbate, thus effecting its release as a free vapor or gas. Thedesorbed gas thus freed is pumped by a compressor 331 through a heater39 for release through an orifice meter lil and delivery through pipe4i. for repressuring the gas supply in a pipe line or for use asdesired. ln some cases it may be desirable to store and desorb gas atpressures slightly higher vthan the pressure of the liuc into which thedesorbed gas will be injected.

Y case the'compressor 3.8 will not be required.

ln addition to storage of methane, the invention involves separation ofmethane and/ or other hydrocarbons in natural gas, from nitrogen which,as above stated, oc'- curs in the natural gas in variable amounts fromcertain natural gas iield sources. The nitrogen not being combustibleand having no heat value value of the natural gas mixture on a volumebasis. Therefore, nitrogen is usually and justly regarded as anundesirable diluteut or impurity. To avoid the expense handling thenitrogen through a pipeline transmission and distribution system, thenitrogen should be removed.

i have found that nitrogen and methane or' a natural gas mixture can beseparated by means of the adsorbent bed when the gas mixture is parsedthrough a bed ot solid adsorbent with both the mixture and the adsorbentbed a lesser extent as shown in Example 4 hereinafter in- Y. theadsorbent practical to Til' ' adsorbent bed as a free gas.

vgas from the pile of solid at'temperatures just above the'liquefactiontemperature oi methane at the contact pressure. Under these temperatureconditions, the methane is adsorbed on the adsorbent as an adsorbate,but the nitrogen is'adsorbe-:l to

eluded and the unadsorbed nitrogeupasses through the rthe nitrogen soreleased can then be disposed of as required under the operatingconditions, if it has no further value. Provision is made as shown onthe diagram to vent gases from the adsorbent bed back to the pipe linethrough pipe 42 that connects the pipe 22 with the pipe line l at apoint up stream from the connection ofthe pipe 4. f

After processing a methane-nitrogen natural gas mii:-V

ture as described, the adsorbent eventually becomes saturated with themethane adsorbate, and no longer removes methane from the gas mixtureunder circulation.

The valuable methane adsorbate can be recovered from when needed bycirculating gas through the adsorbent bed at a temperature higher thanthe separation or adsorbing temperature in the `same manner aspreviously described.

Attention is directed tothe fact that it is possible and desorb at achanged pressure than the adsorption pressure, thus altering theequilibrium to desorb a more favorable temperature or pressure, however,under normal operating conditions desorptionwould be accomplished atadsorption pressure.

If the container of the adsorbent should rupture and the adsorbent spillout on the ground it will not flow as a liquid nor will the gas escaperapidly as a free gas. The adsorbent will merely accumulate in a pile asa solid at the location where it is spilled. On exposure to atmospherictemperatures, the methane will escape slowly as a material. This isbecause the latent heat of desorption required to release the gas fromthe adsorbent'as Vapor must be obtained from the atmosphere or othersource.V

The results of tests to determine the quantity of methane and nitrogenadsorbed under various conditions are illustrated by the followingexamples:

Example 1 Results on Athe adsorption or' the adsorbate methane.

in this decreases the E. t. u.;

on the adsorbent attapulgite (activated at' 316 C., 30/60 mesh):

Capacity of adsorbent for adsorbate methane, CH4, at 800 mm. Hg pressureTemperature in Degrees Centigrade +25 C l60 C 16.5 Inl/gram. 340ml./gram.

Example 2 Results on the adsorption of the adsorbate methane on theadsorbent carbon (commercial sample, 20/60 mesh):

Capacity of adsorbent for adsorbate methane, CH4, at 800 mm. Hg pressureTemperature in Degrees Centigrade +25 C 17.7 Inl/gram. -l59 C 335Inl/gram.

Example 3 Results on the adsorption of the adsorbate methane, on theadsorbent bauxite (activated at l100 F. 20/60 mesh):

Capacity of adsorbent for adsorbate methane, CIEM, at 800 mm. Hgpressure Temperature in Degrees Centlgrade 12.0 nil/gram. 145 mL/gram.

Capacity of Adsorbent for adsorbate at 800 mm. Hg pressure Temperaturein Degrees Centigrade 16.5 ml./g'ram. 340 ELL/gram.

17.4 mL/g'ram. 21.1 Inl/gram.

It is to be emphasized that the drawing is schematic and has been madeas simple as possible for illustrative purposes and it is obvious thatvarious bypasses, automatic controls, valves, etc., are used to obtainthe most advantageous heat balance and design consistent with economics,engineering, local gas pressures and temperatures and other attendantlocal gas pressures and temperatures. Such additions, however, will notchange the principles of the invention as herein described.

From the foregoing it is obvious that I have provided a practical, safeand economical method of storing methane or natural gas throughadsorption by a solid adsorbent material at moderate pressures and atemperature slightly above the liquefaction temperature of methane atthe pressure used. It is also obvious that the adsorbed gas is readilyreleased for use when it is desired to augment the iiow volume in a pipeline at times of high demand for gas.

While l have specically illustrated and described the adaption of myinvention to the storage and stock piling of natural gas, it is obviousthat other gases may be stored in like manner by maintaining atemperature suitable for holding the gas as an adsorbate in an adsorbentmaterial.

What l claim and desire to secure by Letters Patent is:

l. The method of storing a high pressure natural gas on a solidadsorbent material at substantially atmospheric pressure including,liquefying the gas, bringing the liqueied gas into contact with a solidadsorbent material to effect adsorption of liquefied gas on saidmaterial, recirculating any vapor evolved during the adsorption to theplace of liquefaction, and returning said vapors as' a liquid to theplace of adsorption to perature for holding the gas storage period.

2. The method of storing natural gas on a solid adsorbent material andreleasing the natural gas from storage when needed for use including,liquefying the gas, bringing the liquefied gas into contact with a solidadsorbent material to etfect adsorption turning any nnadsorbed gas tothe place of liquefaction, circulating the liquefied gas to the place ofadsorption to maintain the adsorbent at a temperature for holding theabsorbed gas in said material While in storage, and heating theadsorbent material to release gas when gas is needed for use.

3. An apparatus for storing natural gas including a closed vessel,insulating material lining the interior of the vessel for providing aninsulated chamber in said vessel, a body of solid adsorbent materialcontained in said chamber, refrigerating means for cooling the naturalgas to near the liquefaction temperature of the gas at the pressure tobe maintained on said gas, means for condensing the gas after beingcooled by said refrigerating means, duct means for supplying natural gasfor passage through exchange between the gas supply and the unadsorbedgas, and a compressor in said rst named duct means for ei'rectperatureto hold said natural gas as an adsorbate.

4. An apparatus for storing natural gas including a closed vessel,insulating material lining the interior of the vessel for providing aninsulated chamber in said vessel, a body of solid adsorbent materialcontained in said chamber, gas refrigerating means for cooling thenatural gas to near the liquefaction temperature of the gas at thepressure to be maintained on said gas, means for condensing the gasafter being cooled by the refrigerating means, duct means for supplyingnatural gas for passage through the refrigerating means and condensingmeans to the chamber of said vessel, duct means for withdrawingunadsorbed gas from said chamber and returning the unadsorbed gas to therefrigerating change between the gas supply compressor interconnectingsaid duct means for eiecting movement of the gas supply and unadsorbedgas through the refrigerating means to the storage chamber formaintaining said adsorbent at a temperature to hold said natural gas asan adsorbate, and a separator between the refrigerating and condensingmeans and said storage chamber for removing condensate and solidmaterials which might result from cooling of the gas by saidrefrigerating means.

5. An apparatus for storing natural closed insulated vessel, a body ofsolid adsorbent material contained in said vessel, gas refn'gerating ncans for cooling the natural gas to near the liquefaction temperature ofthe gas at the pressure to be maintained on said gas, duct means forsupplying natural gas for passage through the refrigerating means, meansin said duct means for removing any objectionable materials from thegas, a condenser between the last named means and the vessel forcondensing the cooled gas, duct means for withdrawing unadsorbed gasfrom said vessel and returning the ungas including a Vexchange betweenthe gas supply and the unadsorbed gas,

and a compressor in said rst named duct means for effecting movement ofthe gas supply and unadsorbed gas Vthrough the refrigerating means tothe storage vessel for maintaining said adsorbent at a temperature tohold said natural gas as an adsorbate, Y

6. The method of storing a high pressure natural gas on a solidadsorbent material at substantially low pressure and temperatureincluding, cooling the gas to liquify the gas, bringing the liquied gasinto contact with the solid adsorbent material to cool said adsorbentmaterial and to be adsorbed thereby, removing gas that vaporizesincidental to cooling ot the adsorbent material, mixing the vaporizedgas with the incoming gas, and liquiiying said mixture for adsorption bythe adsorbent material.

7. The method of storing a high pressure natural gas on a solidadsorbent material at substantially low pressure including, cooling thegas to the liquication temperature of the gas, bringing the liquied gasinto Contact with the solid adsorbent material to cool said adsorbentmaterial and to be absorbed thereby, removing gas that vaporizesincidental to cooling of the adsorbent material, bringing the vaporizedgas into heat exchange relation with the incoming warm gas, and mixingthe vaporized gas after said heat exchange with the incoming gas to theplace of liquitication.

8. The method of storing a high pressure natural gas on a solidadsorbent material at substantially low pressure including, cooling thegas to a temperature near the liquication temperature of the gas,removing objectionable material from the cooled gas, further reducingthe ternperature to liquity the gas, bringing the liquitied gas intocontact with the solid absorbent material to cool said afsorbent:rmaterial and to be adsorbed thereby, removing gas that vaporizesincidental to cooling and maintaining temperature of the absorbent irc-mthe place o adsorption, bringing the vaporized gas into heat exchangerelation with the incoming Warm gas, and mixing the vaporized gas withthe incoming gas to the place of cooling.

9. The method of storing a high pressure natural gas on a solidadsorbent material at substantially low pressure and temperatureincluding, cooling the gas to liquify the gas, bringing the liquitiedgas into contact with the solid adsorbent material to cool saidadsorbent material and to be adsorbed thereby, removing gas thatvaporizes incidental to cooling of the adsorbent material, mixing thevaporized gas with the incoming gas, liquifying said mixture forIadsorption by the adsorbent material, and passing heated gais intocontact with the adsorbent material when the adsorbed gas is to -bereleased 4from storage.,`

10. The method of storingV ahigh pressure natural gas on a solidadsorbent material atV substantially low pressure including, cooling thegas to liquity the gas, bringing the liquiried gas into contact with thesolid adsorbent Vmaterial to cool said adsorbent material and to beabsorbed thereby, removing gas Vaporized incidental to cooling theadsorbent from the placeof adsorption, bringing the vapoi-ized gas intoheat exchange relation with the incoming warm gas, mixing the vaporizedgas after said heat exchange with the incominggas, liquiying the mixtureat the placent cooling, passing the liquied mixture into contact withthe `cold adsorbent material, and passing heated gas into Contact `withtheragdsorbred material whenthe absorbed gas is to be released fromstorage.- Y

ll. The method of storing a high press ire natural gas on a solidadsorbent material at low temperature and presv sure including, coolingthe gas to a temperature near the liquication temperature of the gas,removing objectionable matter from the cooled gas, Vcondensing the gas,bringing the condensed gas into Contact with the solid adsorbentmaterial to cool said adsorbent material, removing yaporized gas fromthe place of adsorption, bringing the vaporized gas into heatl exchangerelation with. the incoming Warm gas, and mixing the vaporized gas aftersaid 'neat exchange with the incoming gas. t

Reerences Cited inthe le o this'patent UNlTED STATES PATENTS

1. THE METHOD OF STORING A HIGH PRESSURE NATURAL GAS ON A SOLIDADSORBENT MATERIAL AT SUBSTANTIALLY ATMOSPHERIC PRESSURE INCLUDING,LIQUEFYING THE GAS, BRINGING THE LIQUEFIED GAS INTO CONTACT WITH A SOLIDADSORBENT MATERIAL TO EFFECT ADSORPTION OF LIQUEFIED GAS ON SAIDMATERIAL, RECIRCULATING ANY VAPOR EVOLVED DURING THE ADSORPTION TO THE